The present invention is directed to a pressure modulating valve assembly and more particularly to an electrically operated valve supporting member which is mounted in rolling contact with a yoke of a solenoid coil in response to the operation of the solenoid coil to modulate pressure in a valve chamber.
A conventional pressure modulating valve is disclosed in U.S. Pat. No. 4,249,457 granted Feb. 10, 1981 and entitled "Vacuum Servo Motor". In the conventional pressure modulating valve assembly, an armature of magnetic material having recesses at opposite sides thereof is pivoted on a yoke member by means of upstanding projections formed at opposite sides of the yoke whereby the projections are loosely fitted within the recesses, respectively. A valve supporting member of non-magnetic material is secured to the armature and is provided with valve members at opposite ends thereof. Spring means are provided for biasing the armature to a first position wherein one of the valve members engages a valve seat and a solenoid coil is provided for biasing the armature to a second position against the force of the spring means to move the other valve member into engagement with a valve seat while moving the first mentioned valve member out of engagement with its respective valve seat. In the foregoing arrangement, the durability of the valve is lessened since the recesses of the armature and the projections on the yoke are quickly worn by the constant rubbing action which occurs on every rotation of the armature. Such wear eventually leads to undesirable tolerances which adversely affect the seating of the valve members on their respective seats.